Timed Analysis of Security Protocols

We propose a method for engineering security protocols that are aware of timing aspects. We study a simplified version of the well-known Needham Schroeder protocol and the complete Yahalom protocol, where timing information allows the study of different attack scenarios. We model check the protocols using UPPAAL. Further, a taxonomy is obtained by studying and categorising protocols from the well known Clark Jacob library and the Security Protocol Open Repository (SPORE) library. Finally, we present some new challenges and threats that arise when considering time in the analysis, by providing a novel protocol that uses time challenges and exposing a timing attack over an implementation of an existing security protocol

Quantifying pervasive authentication: the case of the Hancke-Kuhn protocol

As mobile devices pervade physical space, the familiar authentication patterns are becoming insufficient: besides entity authentication, many applications require, e.g., location authentication. Many interesting protocols have been proposed and implemented to provide such strengthened forms of authentication, but there are very few proofs that such protocols satisfy the required security properties. The logical formalisms, devised for reasoning about security protocols on standard computer networks, turn out to be difficult to adapt for reasoning about hybrid protocols, used in pervasive and heterogenous networks. We refine the Dolev-Yao-style algebraic method for protocol analysis by a probabilistic model of guessing, needed to analyze protocols that mix weak cryptography with physical properties of nonstandard communication channels. Applying this model, we provide a precise security proof for a proximity authentication protocol, due to Hancke and Kuhn, that uses a subtle form of probabilistic reasoning to achieve its goals.Comment: 31 pages, 2 figures; short version of this paper appeared in the Proceedings of MFPS 201

Towards the Model-Driven Engineering of Secure yet Safe Embedded Systems

We introduce SysML-Sec, a SysML-based Model-Driven Engineering environment aimed at fostering the collaboration between system designers and security experts at all methodological stages of the development of an embedded system. A central issue in the design of an embedded system is the definition of the hardware/software partitioning of the architecture of the system, which should take place as early as possible. SysML-Sec aims to extend the relevance of this analysis through the integration of security requirements and threats. In particular, we propose an agile methodology whose aim is to assess early on the impact of the security requirements and of the security mechanisms designed to satisfy them over the safety of the system. Security concerns are captured in a component-centric manner through existing SysML diagrams with only minimal extensions. After the requirements captured are derived into security and cryptographic mechanisms, security properties can be formally verified over this design. To perform the latter, model transformation techniques are implemented in the SysML-Sec toolchain in order to derive a ProVerif specification from the SysML models. An automotive firmware flashing procedure serves as a guiding example throughout our presentation.Comment: In Proceedings GraMSec 2014, arXiv:1404.163

Proceedings of International Workshop "Global Computing: Programming Environments, Languages, Security and Analysis of Systems"

According to the IST/ FET proactive initiative on GLOBAL COMPUTING, the goal is to obtain techniques (models, frameworks, methods, algorithms) for constructing systems that are flexible, dependable, secure, robust and efficient. The dominant concerns are not those of representing and manipulating data efficiently but rather those of handling the co-ordination and interaction, security, reliability, robustness, failure modes, and control of risk of the entities in the system and the overall design, description and performance of the system itself. Completely different paradigms of computer science may have to be developed to tackle these issues effectively. The research should concentrate on systems having the following characteristics: • The systems are composed of autonomous computational entities where activity is not centrally controlled, either because global control is impossible or impractical, or because the entities are created or controlled by different owners. • The computational entities are mobile, due to the movement of the physical platforms or by movement of the entity from one platform to another. • The configuration varies over time. For instance, the system is open to the introduction of new computational entities and likewise their deletion. The behaviour of the entities may vary over time. • The systems operate with incomplete information about the environment. For instance, information becomes rapidly out of date and mobility requires information about the environment to be discovered. The ultimate goal of the research action is to provide a solid scientific foundation for the design of such systems, and to lay the groundwork for achieving effective principles for building and analysing such systems. This workshop covers the aspects related to languages and programming environments as well as analysis of systems and resources involving 9 projects (AGILE , DART, DEGAS , MIKADO, MRG, MYTHS, PEPITO, PROFUNDIS, SECURE) out of the 13 founded under the initiative. After an year from the start of the projects, the goal of the workshop is to fix the state of the art on the topics covered by the two clusters related to programming environments and analysis of systems as well as to devise strategies and new ideas to profitably continue the research effort towards the overall objective of the initiative. We acknowledge the Dipartimento di Informatica and Tlc of the University of Trento, the Comune di Rovereto, the project DEGAS for partially funding the event and the Events and Meetings Office of the University of Trento for the valuable collaboration

A semantic analysis of key management protocols for wireless sensor networks

Gorrieri and Martinelli's timed Generalized Non-Deducibility on Compositions (tGNDC) schema is a well-known general framework for the formal verification of security protocols in a concurrent scenario. We generalise the tGNDC schema to verify wireless network security protocols. Our generalisation relies on a simple timed broadcasting process calculus whose operational semantics is given in terms of a labelled transition system which is used to derive a standard simulation theory. We apply our tGNDC framework to perform a security analysis of three well-known key management protocols for wireless sensor networks: \u3bcTESLA, LEAP+ and LiSP

Development of security strategies using Kerberos in wireless networks

Authentication is the primary function used to reduce the risk of illegitimate access to IT services of any organisation. Kerberos is a widely used authentication protocol for authentication and access control mechanisms. This thesis presents the development of security strategies using Kerberos authentication protocol in wireless networks, Kerberos-Key Exchange protocol, Kerberos with timed-delay, Kerberos with timed-delay and delayed decryption, Kerberos with timed-delay, delayed decryption and password encryption properties. This thesis also includes a number of other research works such as, frequently key renewal under pseudo-secure conditions and shut down of the authentication server to external access temporarily to allow for secure key exchange. A general approach for the analysis and verification of authentication properties as well as Kerberos authentication protocol are presented. Existing authentication mechanisms coupled with strong encryption techniques are considered, investigated and analysed in detail. IEEE 802.1x standard, IEEE 802.11 wireless communication networks are also considered. First, existing security and authentication approaches for Kerberos authentication protocol are critically analysed with the discussions on merits and weaknesses. Then relevant terminology is defined and explained. Since Kerberos exhibits some vulnerabilities, the existing solutions have not treated the possibilities of more than one authentication server in a strict sense. A three way authentication mechanism addresses possible solution to this problem. An authentication protocol has been developed to improve the three way authentication mechanism for Kerberos. Dynamically renewing keys under pseudo-secure situations involves a temporary interruption to link/server access. After describing and analysing a protocol to achieve improved security for authentication, an analytical method is used to evaluate the cost in terms of the degradation of system performability. Various results are presented. An approach that involves a new authentication protocol is proposed. This new approach combines delaying decryption with timed authentication by using passwords and session keys for authentication purposes, and frequent key renewal under secure conditions. The analysis and verification of authentication properties and results of the designed protocol are presented and discussed. Protocols often fail when they are analysed critically. Formal approaches have emerged to analyse protocol failures. Abstract languages are designed especially for the description of communication patterns. A notion of rank functions is introduced for analysing purposes as well. An application of this formal approach to a newly designed authentication protocol that combines delaying the decryption process with timed authentication is presented. Formal methods for verifying cryptographic protocols are created to assist in ensuring that authentication protocols meet their specifications. Model checking techniques such as Communicating Sequential Processes (CSP) and Failure Divergence Refinement (FDR) checker, are widely acknowledged for effectively and efficiently revealing flaws in protocols faster than most other contemporaries. Essentially, model checking involves a detailed search of all the states reachable by the components of a protocol model. In the models that describe authentication protocols, the components, regarded as processes, are the principals including intruder (attacker) and parameters for authentication such as keys, nonces, tickets, and certificates. In this research, an automated generation tool, CASPER is used to produce CSP descriptions. Proposed protocol models rely on trusted third parties in authentication transactions while intruder capabilities are based on possible inductions and deductions. This research attempts to combine the two methods in model checking in order to realise an abstract description of intruder with enhanced capabilities. A target protocol of interest is that of Kerberos authentication protocol. The process of increasing the strength of security mechanisms usually impacts on performance thresholds. In recognition of this fact, the research adopts an analytical method known as spectral expansion to ascertain the level of impact, and which resulting protocol amendments will have on performance. Spectral expansion is based on state exploration. This implies that it is subject, as model checking, to the state explosion problem. The performance characteristics of amended protocols are examined relative to the existing protocols. Numerical solutions are presented for all models developed

Process Algebras

Process Algebras are mathematically rigorous languages with well defined semantics that permit describing and verifying properties of concurrent communicating systems. They can be seen as models of processes, regarded as agents that act and interact continuously with other similar agents and with their common environment. The agents may be real-world objects (even people), or they may be artifacts, embodied perhaps in computer hardware or software systems. Many different approaches (operational, denotational, algebraic) are taken for describing the meaning of processes. However, the operational approach is the reference one. By relying on the so called Structural Operational Semantics (SOS), labelled transition systems are built and composed by using the different operators of the many different process algebras. Behavioral equivalences are used to abstract from unwanted details and identify those systems that react similarly to external experiments